Too much back pressure?
Thread Starter
Staging Lane
Joined: Jan 2016
Posts: 56
Likes: 14
Too much back pressure? Hit the dyno.... numbers not that great.
I’m thinking the small turbine housings (.64 ar) is just too small.
Here is the the setup
L33 5.3 (aluminum block)
Wiseco flat top pistons
K1 rods
LS2 intake
1000cc FIC injectors
walbro 525
Haltech 2500
BTR stage 1 TT cam/spring/ti retainer
Summit SFI balancer
LS9 head gaskets
ARP head studs
6262 billet turbos .63 vband housings
38mm v band gates
RXT twin plate clutch
T56 magnum
dual 3" i to single 4" exhaust with vibrant muffler
Made 477whp at 13psi with 14deg of timing and 535whp at 15psi with 14deg as well. We felt the car wasn’t making the power it should so we stopped. Was expecting around 600ish at 13psi.
Want to check back pressure and probably swap to the 1.05 stainless v band housing.
I’m thinking the small turbine housings (.64 ar) is just too small.
Here is the the setup
L33 5.3 (aluminum block)
Wiseco flat top pistons
K1 rods
LS2 intake
1000cc FIC injectors
walbro 525
Haltech 2500
BTR stage 1 TT cam/spring/ti retainer
Summit SFI balancer
LS9 head gaskets
ARP head studs
6262 billet turbos .63 vband housings
38mm v band gates
RXT twin plate clutch
T56 magnum
dual 3" i to single 4" exhaust with vibrant muffler
Made 477whp at 13psi with 14deg of timing and 535whp at 15psi with 14deg as well. We felt the car wasn’t making the power it should so we stopped. Was expecting around 600ish at 13psi.
Want to check back pressure and probably swap to the 1.05 stainless v band housing.
TECH Regular
Joined: Dec 2020
Posts: 427
Likes: 133
From: Ohio
250 to 270 wheel NA is what that would be about. You picked up 58 with 2lbs and no timing. Sounds like you're getting in the turbo sweet spot.
I'm not a tuner or an expert but this seems normal to me. If you want 600 hp why not simply turn it up a notch? I'd guess those turbos would max between 650 and 800 rear wheel
I'm not a tuner or an expert but this seems normal to me. If you want 600 hp why not simply turn it up a notch? I'd guess those turbos would max between 650 and 800 rear wheel
Thread Starter
Staging Lane
Joined: Jan 2016
Posts: 56
Likes: 14
you could be right. The first 3 plugs is when we were at 477whp. And the last two is when we added some timing to the 15psi. So adding the two psi only added a bit. Then we tried for more with the timing.
figured the back pressure was getting high and called it a day.
looking at others with twin 6262’s they sell making a lot more power. They seem to make 700-800 at 17 psi. And I have also seen them make 1050 at 24psi
250 to 270 wheel NA is what that would be about. You picked up 58 with 2lbs and no timing. Sounds like you're getting in the turbo sweet spot.
I'm not a tuner or an expert but this seems normal to me. If you want 600 hp why not simply turn it up a notch? I'd guess those turbos would max between 650 and 800 rear wheel
I'm not a tuner or an expert but this seems normal to me. If you want 600 hp why not simply turn it up a notch? I'd guess those turbos would max between 650 and 800 rear wheel
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Staging Lane
Joined: Jan 2016
Posts: 56
Likes: 14
Thread Starter
Staging Lane
Joined: Jan 2016
Posts: 56
Likes: 14
that’s what I was thinking should be 300-340 NA with a manual. I’ll see if I can get the graph from the shop.
Talked with another tuner. He has tuned a 5.3 with the same turbos. He said with the .64 at at 7psi the back pressure was 1.6:1
then they swapped the .84 housings made 40hp more at the same 7psi and the ratio went down to 1.2:1
that’s what I was thinking should be 300-340 NA with a manual. I’ll see if I can get the graph from the shop.
Talked with another tuner. He has tuned a 5.3 with the same turbos. He said with the .64 at at 7psi the back pressure was 1.6:1
then they swapped the .84 housings made 40hp more at the same 7psi and the ratio went down to 1.2:1
Talked with another tuner. He has tuned a 5.3 with the same turbos. He said with the .64 at at 7psi the back pressure was 1.6:1
then they swapped the .84 housings made 40hp more at the same 7psi and the ratio went down to 1.2:1
Thread Starter
Staging Lane
Joined: Jan 2016
Posts: 56
Likes: 14
something happened with Mohawk 94. They had to stop selling it. I think because it was getting thar rating because of the ethanol
Last edited by Fallguy; May 6, 2021 at 11:42 AM.
Not sure why people would want non E fuel, more E the better! I agree .64 is a darn small housing, the larger ones would let it breath better. I run dual vband .96's on mine, runs better than when I had smaller .86 flanged units on there. What's your HP goal?
Thread Starter
Staging Lane
Joined: Jan 2016
Posts: 56
Likes: 14
As for goals I was thinking 600-650 on pump and 800ish on e85
yeah we have it up in Canada. It’s non e 94. I hear it’s pretty good. But I’m not too sure. Could try shell 93. Apparently we are getting e85 this year.
something happened with Mohawk 94. They had to stop selling it. I think because it was getting thar rating because of the ethanol
something happened with Mohawk 94. They had to stop selling it. I think because it was getting thar rating because of the ethanol
Should be easily achievable! Once you get E85 you'll never look back, for 800'ish you can always do E50 for a nice balance of cooling, MPG, and timing.
Thread Starter
Staging Lane
Joined: Jan 2016
Posts: 56
Likes: 14
Thread Starter
Staging Lane
Joined: Jan 2016
Posts: 56
Likes: 14